Wonderboy Cheats
for Game Gear

Level Select

Hold Down-left,1,2 and Start all together while turning on your GameGear. At the title
screen, release Start then press it again (while still holding down the
other buttons). You will go to the round screen as usual, but as long as
you hold 1 and 2 it will stay on this screen.
Now relase down-left on the pad, and use Up and Down on the control pad to
change the round and level number. You can't get to level 10 though,
because you need all the dolls to get there. The furthest you can go is
level 9-4.